Terminal clamp for electrical conductors

ABSTRACT

A terminal clamp for electrical conductors has a cylindrical clamping member which can be rotated in a clamping frame to clamp the conductor. The conductor is inserted into a conductor insertion opening disposed beyond the cylindrical surface of the clamping member. The opening extends in the longitudinal direction of the clamping member. The clamping surfaces of the cylindrical clamping member are eccentrically arranged in such a manner that they protrude beyond the cylinder surface of the clamping member and clamp a conductor inserted into the conductor opening against the clamping frame when the clamping member is rotated. The tool which is used to rotate the clamping member is then positioned in a direction parallel to the direction in which the conductor is inserted.

United States Patent Galli Mar. 25, 1975 [75] Inventor: AntonGaIli,Schwandorf, Germany [73] Assignee: Siemens Aktiengesellschaft,Munich,

Germany [22] Filed: Aug. 29, 1973 [21] Appl. No.: 392,522

[30] Foreign Application Priority Data Sept. 4, 1972 Germany 2243454[52] U.S. Cl. 339/274, 339/95 R, 24/134 R [51] Int. Cl. H01r 7/06, HOlr9/08 [58] Field of Search 339/95, 96, 97 R, 98, 236, 339/238-240, 247,273, 274; 24/134 R [56] References Cited UNITED STATES PATENTS 1,537,0665/1925 Callender et al 339/95 B 2,125,203 7/1938 Schanbacher 339/2392,314,219 3/1943 Johnson 339/239 2,698,424 12/1954 Allen 339/2392,763,847 /1956 Hubbell 339/274 2,816,155 12/1957 Barnes 24/134 R XFOREIGN PATENTS OR APPLICATIONS 981,844 l/1951 France 24/134 R 534,05112/1921 France ..339/273S Primary Examiner-Francis K. Zugel AssistantExaminer-Lawrence .l. Staab Attorney, Agent, or Firml(enyon & KenyonReilly Carr & Chapin [57] ABSTRACT A terminal clamp for electricalconductors has a cylindrical clamping member which can be rotated in aclamping frame to clamp the conductor. The conductor is inserted into aconductor insertion opening disposed beyond the cylnindrical surface ofthe clamping member. The opening extends in .the longitudinal directionof the clamping member. The clamping surfaces of the cylindricalclamping member are eccentrically arranged in such a manner that theyprotrude be yond the cylinder surface of the clamping member and clamp aconductor inserted into the conductor opening against the clamping framewhen the clamping member is rotated. The tool which is used to rotatethe clamping member is then positioned in a direction parellel to thedirection in which the conductor is inserted.

12 Claims, 9 Drawing Figures PATENTEBHARZSHYS 3,873,178

: r g 13 H7 15 Fig-5 Fig.9

TERMINAL CLAMPFOR ELECTRICAL CONDUCTORS BACKGROUND OF THE INVENTION Theinvention relates to a terminal clamp for electrical conductors with acylindrical clamping member which can be rotated in a clamping frame andhas eccentrically arranged clamping surfaces. Deutsche Gebrauchsmuster1,971,099 discloses a terminal clamp of this type wherein there is anessentially cylindrical clamping part which is rotatably supported inthe bottom opening of a cup-shaped clamping frame and has a groove whichis provided on the periphery of the cylindrical clamping part. Thegroove receives a conductor and extends in helix-fashion around the axisof rotation and at the same time becomes narrower. In this terminalclamp the direction of insertion of the conductor and the direction ofapplying a tool for turning the clamping part, for instance, a screwdriver in the operating slot of the clamping part are therefore at rightangles to each other. With the known terminal clamp it is furthermoreonly possible to clamp one conductor in the eccentric groove, forinstance, a contact inserted into the cup, and the conductor must fitthe dimensions of the groove. Furthermore, the cup is solid, so that abackward rotation of the eccentric cannot be pre vented reliably,particularly in the presence of vibrations or when temperaturevariations occur, because the conductor clamping part and the clampingframe consist of different material.

SUMMARY OF THE INVENTION It is therefore an object of the invention toprovide a terminal clamp of the above-mentioned type wherein thedirection of operating the clamp and the direction of inserting theconductor to be clamped are parallel to each other so that the terminalitself requires relatively little space and still functions reliably.

Accordingto a feature of the invention, the eccentrically arrangedclamping surfaces protrude beyond the cylinder. Further, the clampingframe has at least one conductor insertion opening disposed outside thecylinder in the longitudinal direction of the cylinder.

Terminal clamp of the invention includes a cylindrical clamping memberhaving a cylindrical surface and defining a longitudinal axis. Aclamping frame accommodates the clamping member and defines at least oneinsertion opening for receiving an electrical conductor therein. Theopening extends in the direction of the above-mentioned longitudinalaxis and is located be yond the cylindrical surface of the clampingmember. The clamping member is rotatably mounted in the clamping framefor clamping the conductor and has a portion which protrudeseccentrically from the cylindrical surface to define at least oneclamping surface.

Particularly for clamping several conductors to each other or to acontact piece inserted into the clamping frame, it is advantageous ifthe clamping frame is resilient. The manufacture of the terminal clampaccording to the invention, and especially the assembly of the clampingcylinder in the clamping frame, is facilitated considerably if theclamping frame is made up of a U- shaped guide part for accommodatingthe clamping member and a pressure plate which closes the U and isfastened to the guide part. If the guide part and the pressure plate arehooked into each other additional assembly steps are unnecessary. Therequired space and material can be reduced furtherif. for instance. theguide member and the pressure plate are joined together by peening.

It is advantageous that the pressure plate is notjoincd to the clampingframe rigidly, more specifically, the clamping frameitself can twistbecause then the pressure plate can adapt itself to the pitch of theeccentric portion of the clamping member when two conductors areconnected.

The bearing of the clamping member is improved when the clamping frameis configured to have bent-in portions between where the clamping memberis mounted and where the conductor is accommodated. These bent-inportions are particularly advantageous for the resiliency of theclamping frame and for matchingto the pitch of the eccentric portion ifat least parts of the clamping frame are made of spring steel.Additional security against the conductor being pulled out is providedby a terminal clamp configuration in which the eccentrically arrangedclamping surfaces around the cylindersurface are disposed at an angle tothe longitudinal axis of the latter.

Symmetrical pressure conditions can beobtained in such a configurationwhen two clamping surfaces are arranged about the cylinder surface andwhen their respective planes intersect to define an obtuse angle.Defined contact surfaces for a conductor to be clamped and a shorteningof the lift of the eccentric portion in the case of two conductors ofsmaller cross-section can be obtained if the pressure plate is curvedaway from the clamping member.

Although the invention is illustrated and described herein as terminalclamp for electrical conductors, it is nevertheless not intended to belimited to the details shown, since various modifications may be madetherein within the scope and the range of the claims. Theinvention,however, together with additional objects and advantages will be bestunderstood from the following description and in connection with theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of theterminal clamp according to the invention. The clamp is shown in itsopen position.

FIG. 2 shows the terminal clamp with one conductor inserted therein.

FIG. 3 shows the terminal clamp with two conductors inserted therein,the conductors having a cross-section less than the conductor shown inFIG. 2.

FIGS. 4 and 5 show respectively a plan view and an end view of theU-shaped guidance part of the clamping frame.

FIGS. 6 and 7 show respectively a front view and an elevation view ofthe pressure plate which is connected to the guidance part.

FIGS. Sand 9 show respectively a front view and an elevation view of theclamping member and the portion thereof defining the eccentricclampingsurfaces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring toFIG. 1, the clamping frame 1 of the terminal clamp according to theinvention includes the guide part 2 for the cylindrical clampingmember 3having an eccentrically disposed clamping surface 4. The frame 1 furtherincludes a pressure plate 5 which is hooked into the arms 6 of the guidepart 2. For this purpose an opening 7 is provided in the arm 6 as shownin FIG. 5, into which projections 8 of the pressure plate are hung. Thepressure plate 5 is, for instance, slightly curved at its centerportion, as shown in FIGS. 6 and 7.

A contact element 9, preferably aconducting bar, which can be broughtinto conducting contact with conductors 10 or 11, is inserted into thepressure plate 5 in the embodiment of FIGS. 1 to 3. The clamping surfaces 4 are provided at an eccentric portion 12 formed on thecylindrical clamping member 3 which protrudes through a cutout 13 shownin FIG. 5. The webs 14 between the opening 7 and the cutout l3 serve asstops for the eccentric portion 12 in the fully opened condi tion shownin FIG. 1. The pitch of the eccentric portion 12 and therefore, theposition of the clamping surfaces with respect to the pressure plate 5is chosen so that self-locking takes place. However, it is advantageous,provided the U-shaped guide part is resilient and, for instance,consists of spring steel, to provide bent-in portions 15 at the arms 6which yield if the terminal is tightened; this action connects theconductors 10 and /or 11 reliably with the contact element 9 also in thepresence of temperature variations and vibration.

As shown in FIGS. 8 and 9, the clamping surfaces 4 can be disposed at anangle to the cylindrical surface of the clamping member 3. In theillustrated embodiment, these are two ring surfaces about thecylindrical surface which conjointly define an obtuse angle so that theconductor is readily deformed when clamped; this makes it harder to pullthe conductor out of the terminal clamp in the clamped condition.Serrations can be applied to these surfaces.

Referring to FIGS. 1 to 3, the terminal clamp according to the inventionis utilized, for instance, by inserting the conductors 10 into the openterminal clamp and the clamping member 3 is turned to the right to theposition shown in FIG. 3 or, if one conductor is inserted to theposition shown in FIG. 2, for example, by inserting a screw driver intothe slot 16 and turning the same; this causes the bent-in portions 15 torecede slightly which in turn leads to an elastic tightening of theconductors 10 or 11 against the fixed contact 9. The terminal clamp isopened by turning the clamping member 3 to the left.

The terminal according to the invention requires very little space andis particularly well suited for connecting to the rear contacts of thepush buttons.

What is claimed is:

' l. A terminal clamp for electrical conductors, comprising acylinder-like clamping member having a cylindrical surface and defininga longitudinal axis;

a clamping frame including a U-shaped bent guide part for accommodatingsaid clamping member and defining at least one insertion opening forreceiving an electrical conductor therein, said opening extending in thedirection of said axis and being beyond said cylindrical surface. saidclamping frame being configured so as to have bent-in portions betweenwhere said clamping member is disposed and said insertion opening;

said clamping member being rotatably mounted in said clamping framebetween said bent-in portions and the bight of said U-shaped guide partfor clamping the electrical conductor, said clamping member having aneccentric portion protruding eccentrically from the cylindrical surfacethereof to define at least one clamping surface, and

a pressure plate attached to said guide part so as to close the open endof said U-shaped guide part.

2. The terminal clamp of claim 1, said clamping frame being made ofresilient material.

3. The terminal clamp of claim 1, said clamping frame being configuredso as to be bendable into itself.

4. The terminal clamp of claim 1, said guide part and said pressureplate being hooked into each other.

5. The terminal clamp of claim 4, said guide part and said pressureplate being peened to each other.

6. The terminal clamp of claim 1, said pressure plate being arched awayfrom said clamping member.

7. The terminal clamp of claim 1, said clamping frame and said pressureplate being serrated.

8. The terminal clamp of claim 1, said guide part being serrated.

9. The terminal clamp of claim I, said pressure plate being serrated.

10. The terminal clamp of claim 1 wherein at least one of said clampingframe and said pressure plate is made of spring steel.

11. The terminal clamp of claim 1, said eccentric portion of saidclamping member defining clamping surfaces which extend about saidcylindrical surface at an angle to said longitudinal axis.

12. The terminal clamp of claim 11, said clamping surfaces defining anobtuse angle and being disposed on said eccentric portion so as toextend about said cylindrical surface.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,873,178

DATED l March 25, 1.975

INVENTOR(S) I ton Galli it is certified that errer appears m the ahriveidentified patent and that said Letters Patent are hereby corrected asshown below In the Abstract, line 5, change "cylnindrical" to read-cylindrical- In the Abstract, line 15, change "parellel" to readparallel- In Column 3, line 29, change "cylindrical surface" to read--cylinder surface-- Signed and Scaled this Arrest:

RUTH C. MASON Aucsrr'ng Officer C. MARSHALL DANN Commissioner of Parentsand Trademarks

1. A terminal clamp for electrical conductors, comprising acylinder-like clamping member having a cylindrical surface and defininga longitudinal axis; a clamping frame including a U-shaped bent guidepart for accommodating said clamping member and defining at least oneinsertion opening for receiving an electrical conductor therein, saidopening extending in the direction of said axis and being beyond saidcylindrical surface, said clamping frame being configured so as to havebent-in portions between where said clamping member is disposed and saidinsertion opening; said clamping member being rotatably mounted in saidclamping frame between said bent-in portions and the bight of saidUshaped guide part for clamping the electrical conductor, said clampingmember having an eccentric portion protruding eccentrically from thecylindrical surface thereof to define at least one clamping surface, anda pressure plate attached to said guide part so as to close the open endof said U-shaped guide part.
 2. The terminal clamp of claim 1, saidclamping frame being made of resilient material.
 3. The terminal clampof claim 1, said clamping frame being configured so as to be bendableinto itself.
 4. The terminal clamp of claim 1, said guide part and saidpressure plate being hooked into each other.
 5. The terminal clamp ofclaim 4, said guide part and said pressure plate being peened to eachother.
 6. The terminal clamp of claim 1, said pressure plate beingarched away from said clamping member.
 7. The terminal clamp of claim 1,said clamping frame and said pressure plate being serrated.
 8. Theterminal clamp of claim 1, said guide part being serrated.
 9. Theterminal clamp of claim 1, said pressure plate being serrated.
 10. Theterminal clamp of claim 1 wherein at least one of said clamping frameand said pressure plate is made of spring steel.
 11. The terminal clampof claim 1, said eccentric portion of said clamping member definingclamping surfaces which extend about said cylindrical surface at anangle to said longitudinal axis.
 12. The terminal clamp of claim 11,said clamping surfaces defining an obtuse angle and being disposed onsaid eccentric portion so as to extend about said cylindrical surface.